The computer industry utilizes character encoding systems for a variety of languages around the world. One example of a character encoding system used by the computer industry is the Thai API Consortium/Thai Industrial Standard (“TACTIS”) which is used for the Thai language. The TACTIS code set consists of the ASCII (ISO 646-1983) character set and the TIS 620-2533 character set. The TIS 620-2533 character set includes Thai characters categorized as consonants, vowels, tone marks, diacritics, and noncomposibles. Examples of noncomposibles include punctuation marks and Thai digits.
Unlike the developers of the computer industry, developers of portable electronic devices must implement user interfaces having a limited number of keys. Of particular interest are strongly CV-typed languages having a strong consonant-vowel (“CV”) type, such as Thai, Lao, Khmer, Myanmar, Korean, Tibetan, Hebrew, Arabic, and Indian languages such as Hindi and Tamil. Such languages often have a large alphabet and, thus, use many different characters. For example, an interface for Thai must support over 60 characters. On the other hand, portable electronic devices, typically have only twelve or so keys of which ten keys are used for entering the numbers “1” through “9” and “0”. Therefore, it is quite challenging to design a portable electronic device that permits a user to input the numerous characters of a strongly CV-typed language using the limited number of keys in a standard keypad.
Accordingly, there is a need for a keypad entry system for character entry capable of addressing the numerous characters of a strongly CV-typed language. In particular, there is a need for a keypad entry system for character input that distributes consonants and vowels throughout the keypad in an intuitive configuration.